Gist to create a pool of chickens in Unity3D with the help of object pooling pattern

ChickenPoolController.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ChickenPoolController : MonoBehaviour
{
    // holds the pool of chickens
    private List<Chicken> chickenPool = new List<Chicken>();
    // Size of the pool
    [SerializeField]
    private int chickenPoolSize = 100;

    // actual chicken that is part of the pool
    public Chicken chickenPrefab;

    // Start is called before the first frame update
    void Start()
    {
        // filling the pool with chickens
        for (int i = 0; i < chickenPoolSize; i++)
        {
            // create object of chicken
            Chicken chickenObject = Instantiate(chickenPrefab);
            // put chicken in list i.e pool
            chickenPool.Add(chickenObject);
        }
        
    }

    /// <summary>
    /// get on chicken from pool
    /// </summary>
    /// <returns></returns>
    public Chicken GetChicken()
    {
        for (int i = 0; i < chickenPoolSize; i++)
        {
            if(!chickenPool[i].isActiveAndEnabled)
            {
                return chickenPool[i];
            }
        }
        return null;
    }

    // Update is called once per frame
    void Update()
    {
        
    }
}